First, I want to say that I really love your book. But I think there're some places need to be corrected.
+ This sentence: "Each plant should be displayed with information regarding their color, instructions for
watering and a button to mark a plant as watered. We will add" (page 92- line 4 from top), I think you miss something after the word "add".
+ This sentence: "this.status = new ReactiveVar(); " (page 92 - ReactiveVar –The power of Session with a local scope) should be "this.watered = new ReactiveVar();".
+ Another sentence: "In this case the keyword this refers to the currently available data context" (page 92 - ReactiveVar –The power of Session with a local scope) should be "In this case the keyword this refers to the currently template instance."